A private branch exchange (PBX) network connects a series of heterogeneous terminals to a central processing device to process communications between connected terminals. For example, digital telephones, analog telephones, ISDN terminals, computers, VoIP devices and other devices may be connected to the processing element. The processing device may also have a connection to the public telephone network, thereby allowing communications to be processed between a connected terminal and an external device connected to the public telephone network. It will be appreciated that the connected terminals may have different connectivity requirements from each other. For example, different terminals may have different pin-outs for their connectors. It would be advantageous for a processing element to have flexible connection configurations to accommodate connection requirements of the different terminals and different telephone network interfaces.